Shaft lock

ABSTRACT

A shaft lock particularly for auxiliary sailboats and the like has a split flanged-collar clampable to a rotatable shaft provided with a pair of opposed recesses. A pivotally mounted latch member is arranged adjacent the flanged collar for selectively cooperating with the recesses in holding the shaft in one of two opposed positions. A lever member is connected to the latch member by means of a cable for selectively moving the latch member in cooperative engagement with a recess. The lever member is arranged for freely releasing upon a rotation of the shaft from a position wherein the latch member and a recess are in cooperative engagement.

United States Patent [191 Sarns Jan. 22, 1974 [22] Filed:

[ 1 SHAFT LOCK [76] Inventor: Norman M. Sarns, Bass Harbor,

[52] US. Cl. 115/05 R, 114/39 R, 416/169 [51] Int. Cl B6311 9/00 [58]Field of Search 115/05 R, 0.5 A; 188/31, 69,

Primary Examiner-George E. A. Halvosa Assistant Examiner-Sherman D.Basinger Attorney, Agent, or FirmClarence A. OBrien; Harvey B. Jacobson1 [5 7] ABSTRACT A shaft lock particularly for auxiliary sailboats andthe like has a split flanged-collar clampable to a rotatable shaftprovided with a pair of opposed recesses. A pivotally mounted latchmember is arranged adjacent the flanged collar for selectivelycooperating with the recesses in holding the shaft in one of two opposedpositions. A lever member is connected to the latch member by means of acable for selectively moving the latch member in cooperative engagementwith a recess. The lever member is arranged for freely releasing upon arotation of the shaft from a position wherein the latch member and arecess are in cooperative engagement.

12 Claims, 9 Drawing Figures PATENTEB M 22 SHEET 2 BF 2 SHAFT LOCKBACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This inventionrelates generally to a shaft lock, and in particular to a shaft lock forsailboats provided with auxiliary engines, and the like.

1. DESCRIPTION OF THE PRIOR ART A problem commonly encountered withsailboats having an auxiliary engine is that the propeller will spin, orwindmill, as the boat passes through the water with the engine shutdown.This windmilling subjects the gear box of the engine to possibledamaging forces. Further, the movement of a, for example, two-bladescrew propeller from behind the deadwood of the hull of the boat createsdrag affecting the hulls passage through the water.

Devices are knwon, such as shown in U. .8. Pat. Nos. 2,072,764,2,966,244, and 2,984,318, which have a member attachable to the outputshaft of a gear box or transmission for being selectively engaged tohold a vehicle against movement. These known shaft locks have thedisadvantage that they are designed to lock the shaft in a positioncorresponding to a nearly continuous position of the wheels of thevehicle. This arrangement is not suitable for auxiliary sailboats sinceit is desirable to retain the blades of the screw propeller in aposition behind the deadwood of the boat.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a shaft lock particularly for holding the propeller shaft of theauxiliary engine of a sailboat and the like in one of two opposed.positions so as to center a two-blade screw propeller behind thedeadwoodof the boat.

This and other objects are achieved according to the present inventionby providing a shaft lock having a member adapted to be mounted on arotatable propeller shaft which is to be selectively held in apredetermined position or positions. This member has first means forengaging, while second means for engaging are arrangeable adjacent themember for selectively cooperating with the first engaging menas andholding the shaft in, for example, one of two opposed positions. A meansmay be provided for selectively and remotely moving the second engagingmeans into cooperation with the first engaging means.

In a preferred embodiment according to the present invention, the memberadapted to be mounted on the propeller shaft is a split flanged-collarclampable to the shaft, while the first engaging means is a pair ofopposed recesses provided in a face of the flange of the flanged collar.The second engaging means is a pivotally mounted latch memberselectively engageable with these recesses. A bracket pivotally mountsthe latch member, and is in turn adapted to be mounted on a gear boxconnected to the shaft.

A preferred embodiment of the selectively moving means has a levermember, and a cable connected to and extending between the latch memberand the lever member. The selective actuation of the lever member pivotsthe latch member into cooperative engagement with one of said recesses.The lever member is arranged for freely releasing upon a rotation of thepropeller shaft from a position wherein the latch member and a recessare in cooperative engagement.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, schematic topplan view showing an auxiliary sailboat provided with a shaft lockaccording to the present invention.

FIG. 2 is a fragmentary, schematic sectional view taken generally alongthe line 2-2 of FIG. I. I

FIG. 3 is a fragmentary, side elevational view, drawn to a larger scalethan FIGS. 1 and 2 and showing a shaft lock according to the presentinvention.

FIG. 4 is a fragmentary, sectional view taken generally along the line44 of FIG. 3.

FIG. 5 is a fragmentary, detail sectional view taken generally alongline 5-5 of FIG. 3 and drawn to a larger scale.

FIG. 6 is a perspective view showing a device for remotely actuating theshaft lock according to the present invention.

FIG. 7 is a sectional view taken generally along the line 7-7 of FIG. 6.

FIG. 8 is a sectional view taken generally along the line 8-8 of FIG. 6,and showing the remote controlling device of FIG. 6 attached to aportion of an auxiliary sailboat.

FIG. 9 is a sectional view taken generally along the line 99 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 and2 of the drawings, a sailboat 10 is shown having an auxiliary engine 12driving a propeller shaft 14 through a gear box 16. A shaft lock 18according to the present invention is provided for preventingwindmilling of a two-blade screw propeller 20 mounted on shaft 14 whensailboat 10 is under sail (not shown) and engine 12 is shut down.

Referring now to FIGS. 3 to 5 of the drawings, shaft lock 18 has a splitflanged-collar 22 clamped to shaft 14 in a known manner. A pair ofopposed recesses 24 are provided in a face 25 of flanged collar 22 toform a first means for engaging. A pivotally mounted latch member 26 isprovided for selectively engaging with recesses 24 and holding shaft 14in one of two opposed positions which center propeller 20 behind thedeadwood of sailboat 10.

A bracket 28 pivotally mounts latch member 26. This bracket 28 ismounted on gear box 16 as by removing a pair of bolts 30, placing holes(not shown) defined in flange plate 32 of bracket 28 in alignment withthe threaded holes (not shown) normally receiving bolts 30, andreplacing the two bolts 30. A pair of angled struts 34 and a singlecentral strut 36 are connected at one end to flange plate 32 as bywelding, and are coplanar and adjacent at the other end thereof. Thisother end is provided with a bore (not shown) which mates with holes 38provided in latch member 26. Thus, latch member 26 is easily mounted onbracket 28 by inserting a pin 40 through holes 38 and the bore in thestruts 34, 36. A spring 42, which may be a conventional coiled spring,is fastened in a known manner to strut 36 and latch member 26 forbiasing latch member 26 out of cooperative engagement with recesses 24.The flanged collar 22 has a hub 46 having a plurality of threaded holes47 defined therein for receiving setscrews 48. Flanged collar 22 may beclamped to shaft 14 by tightening down setscrews 48 in a known manner.

Returning now to FIG. I and 2 of the drawings, a control lever assembly50 is preferably provided for selectively and remotely moving latchmember 26 into cooperation with a recess 24. Assembly 50 is operativelyconnected to latch member 26 by means of connecting means 52 which willbe described below along with assembly 50.

Turning now to FIGS. 6 to 9 of the drawings, assembly 50 has a housing54 adapted to be mounted on sailboat 10. A lever member 56 'is pivotallymounted in housing 54, and a rope which is preferably a wire rope orcable is operatively connected to lever member 56 and latch member 26. Asheath 60 is preferably arranged about rope 58 in the conventionalmanner for protecting same. The selective actuation of lever member 56pivots latch member 26 into cooperative engagement with one of recesses24 against the bias of spring 42. The bias of spring 42 tends to pivotlatch member 26 out of engagement with the recess 24 when the forceapplied by rope 58 is removed.

Rope, or cable, 58 is attached in a known manner to a cable securer 62.This cable securer 62 is connected to a threaded rod 64, which is inturn connected to the perpendicular leg of a T-member. Screw threads areprovided in at least one of the perpendicular leg of T- member 66 andthe bore of securer 62 which receives rod 64 so that an adjustment isprovided.

Lever member 56 is pivotally mounted in housing 54 as by a pair ofrivets 68. As can best be seen in FIG. 7 of the drawings, a pair oflinks 70, each defining a recess 72 which fits around rivet 68 in theFIG. 6 position of lever member 56, and are pivotally mounted to levermember 56 as by rivets 74. T-member 66 is mounted to links 70 as byopenings 75. When lever member 56 is in the position shown in FIG. 6 ofthe drawings, latch member 26 is normally in engagement with a recess24. However, upon a rotation of shaft 14 sufficient force will beapplied to link 70 to pull lever member 56 into the position shown inFIG. 7 of the drawings. Thus, lever member 56 is arranged for freelymoving upon rotation of shaft 14, and an automatic releasing in such asituation is achieved. Of course, a release may be achieved by manuallymoving lever member 56 to the position shown in FIG. 7, the bias ofspring 42 effecting disengagement.

Housing 54 has an end wall 76 provided with an opening 77. A grommet 78is arranged in opening 77 for anchoring one end of sheath 60 and forguiding rope 58.

FIG. 8 of the drawings shows assembly 50 attached to a portion ofsailboat l0. Fasteners 82 may advantageously be used. In the case of awooden boat, these fasteners 82 may simply be wood screws driven into aboat portion 84 of cockpit 86 (FIG. 2).

FIG. 9 of the drawings shows a fragment of a boat portion 88 to which abracket 90 is mounted as by fasteners 92. Bracket 90 is provided with abore 94 through which rope 58 and sheath 60 may be run and guidedthereby.

Returning now to FIG. 3 of the drawings, a bracket 96 is mounted as bywelding on strut 36 of bracket 28.

A grommet 98 provides an anchor for the other end of sheath 60 andserves as a guide for rope 58. Rope 58 may be passed through a bore 100provided in latch member 26, and is retained therein as by a knot 102. Ashaft lock 18 according to the present invention may be easily installedin a sailboat 10. A pair of bolts 30 may be removed from gear box 16 andbracket 26 attached thereto. Split flanged collar 22 may then bearranged on shaft 14 in a known manner, making sure that latch member 26properly engages recesses 24 be fore setscrews 48 are tightened. Thecontrol lever assembly 50 may be mounted in a convenient place in ornear cockpit 86, preferably in a sail locker. Sheath 60, which may bevinyl lined copper tubing, is led to bracket 90, with care being takento avoid sharp bends therein. Rope 58, which may be, for example, 7(wire) X 9 (strand) stainless steel cable, is led through sheath 60 tocable securer 62. Tension on rope 58 may now be adjusted. This ispreferably done when latch member 26 is engaged with a recess 24. Onlythe pressure of one finger on latch member 26 is necessary to retainpropeller 20 from spinning at the highest sailing speeds. Experience hasfound that once properly installed, a shaft lock 18 according to thepresent invention will require little or no adjustment throughout anentire sailing season. Further, maintenance is minimal, with only anoccasional spray lubrication being required to maintain the equipment. I

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed and accordingly all suitable modifications and equivalents maybe resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. A shaft lock for an auxiliary sailboat, comprising,

in combination:

a. a member adapted to be mounted on a propeller shaft of an auxiliarysailboat, and having first means for engaging; b. second means forengaging arrangeable adjacent said member for selectively cooperatingwith the first engaging means and holding the propeller shaft in aposition centering a propeller associated with the shaft behind deadwoodof the sailboat; and means for selectively moving the engaging meansinto cooperation with one another, and including means for achieving anautomatic releasing of the engaging means upon a rotation of the shaftwhen the engaging means are in cooperative engagement, said member beinga split flanged-collar clampable to said shaft, and said first engagingmeans being a pair of opposed recesses provided in a face of the flangedcollar, and said second engaging means being a pivotally mounted latchmember selectively engageable with the recesses. 2. A structure asdefined in claim 1, further including a bracket pivotally mounting saidlatch member and adapted to be mounted on a gear box connected to theshaft, and means connected to the bracket and the latch member forbiasing the latch member out of cooperative engagement with therecesses.

3. In combination with a sailboat having an auxiliary engine driving apropeller shaft through a gear box, a shaft lock for preventingwindmilling of a two-blade screw propeller mounted on and turned by saidpropeller shaft when the sailboat is under said and the auxiliary enginethereof shut down, said shaft lock comprising, in combination:

a. a member detachably mounted on the shaft, and

having first means for engaging;

b. second means for engaging mounted adjacent said member forselectively cooperating with the first engaging means and holding saidshaft in one of two opposed positions which center said propeller behinddeadwood of the sailboat; and

c. means for selectively moving the engaging means into cooperation withone another, and including means for achieving an automatic releasing ofthe engaging means upon a rotation of the shaft when the engaging meansare in cooperative engagement, 'said member being a split flanged-collarclampable to said shaft, and said first engaging means being a pair ofopposed recesses provided in a face of the flanged collar, and saidsecond engaging means being a pivotally mounted latch member selectivelyengageable with the recesses.

4. A structure as defined in claim 3, further including a bracketpivotally mounting said latch member and adapted to be mounted on thegear box, and means connected to the bracket and the latch member forbiasing the latch member out of cooperative engagement with therecesses.

5. A shaft lock for an auxiliary sailboat, comprising,

in combination:

a. a member adapted to be mounted on a propeller shaft of an auxiliarysailboat, and having first means for engaging, said member being a splitflanged-collar clampable to the shaft and said first engaging means apair of opposed recesses provided in a face of the flanged collar;

b. second means for engaging arrangeable adjacent said member forselectively cooperating with the first engaging means and holding thepropeller shaft in a position centering a propeller associated with theshaft behind the deadwood of the sailboat,

said second engaging means being a pivotally mounted latch memberselectively engageable with the recesses; Y

c. means for selectively moving the second engaging means intocooperation with the first engaging means, the selectively moving meansincluding a lever member and a rope connected to and extending betweensaid latch member and said lever member, the selective actuation of thelever member pivoting said latch member into cooperative engagement withone of said recesses, and said lever member being arranged for freelymoving upon a rotation of the shaft from a position wherein the latchmember and a recess are in cooperative engagement for achieving anautomatic releasing of the latch member from the recess; and

d. a bracket pivotally mounting said latch member and adapted to bemounted on a gear box connected to the shaft, and means connected to thebracket and the latch member for biasing the latch member out ofcooperative engagement with the recesses.

6. A shaft lock for an auxiliary sailboat, comprising,

in combination:

a. a member adapted to be mounted on a propeller shaft of an auxiliarysailboat, and having first means for engaging;

b. second means for engaging arrangeable adjacent said member forselectively cooperating with the first engaging means and holding thepropeller shaft in a position centering a propeller associated with theshaft behind deadwood of the sailboat; and

' c. means for selectively moving the second engaging means intocooperation with the first engaging means, the selectively moving meansincluding a lever member and a rope connected to and extending betweenthe first and second engaging means, the selective actuation of thelever member pivoting said second engaging means into cooperativeengagement with said first engaging means, and said lever member beingarranged for freely moving upon a rotation of the shaft from a positionwhere the engaging means are in cooperative engagement for achieving anautomatic releasing of the engaging means.

7. A structure as defined in claim 6, wherein said member is a splitflanged-collar clampable to the shaft and said first engaging means is apair of opposed recesses provided in a face of said flanged-collar, andsaid second engaging means is a pivotally mounted latch memberselectively engageable with the recesses.

8. A structure as defined in claim 7, further including a bracketpivotally mounting said latch member and adapted to be mounted on a gearbox connected to the shaft, and means connected to the bracket and thelatch member for biasing the latch member out of cooperative engagementwith the recesses.

9. In combination with a sailboat having an auxiliary engine driving apropeller shaft through a gear box, a shaft lock for preventingwindmilling of a two-blade screw propeller mounted on and turned by saidpropeller shaft when the sailboat is under sail and the auxiliary enginethereof shut down, said shaft lock comprising, in combination: 7

a. a member detachably mounted on the shaft, and having first means forengaging said member being a split flanged-collar clampable to saidshaft, and said first engaging means a pair of opposed recesses providedin a face of the flanged collar;

b. second means for engaging mounted adjacent said member forselectively cooperating with the first engaging means and holding saidshaft in one of two opposed positions which center said propeller behinddeadwood of the sailboat, said second engaging means being a pivotallymounted latch member selectively engageable with the recesses;

0. means for selectively moving the second engaging means intocooperation with the first engaging means, the selectively moving meansincluding a lever member and a rope connected to and extending betweensaid latch member and said lever member, the selective actuation of thelever member pivoting said latch member into cooperative engagement withone of said recesses, and said lever member being arranged for freelymoving upon a rotation of the shaft from a position wherein the latchmember and a recess are in cooperative engagement for achieving anautomatic releasing of the latch member from the recess; and

d. a bracket pivotally mounting said latch member and adapted to bemounted on the gear box, and

means connected to the bracket and the latch member for biasing thelatch member out of cooperative engagement with the recesses.

10. In combination with a sailboat having an auxiliary engine driving apropeller shaft through a gear box, a shaft lock for preventingwindmilling of a two-blade screw propeller mounted on and turned by saidpropeller shaft when the sailboat is under sail and the auxiliary enginethereof shut down, said shaft lock comprising, in combination:

a. a member detachably mounted on the shaft, and

having first means for engaging;

b. second means for engaging mounted adjacent said member forselectively cooperating with the first engaging means and holding saidshaft in one of two opposed positions which center said propeller behinddeadwood of the sailboat; and

c. means for selectively moving the second engaging means intocooperation with the first engaging means, the selectively moving meansincluding a lever member and a rope connected to and extending betweenthe first and second engaging means,

the selective actuation of the lever member pivoting said secondengaging means into cooperative engagement with said first engagingmeans, and said lever member being arranged for freely moving upon arotation of the shaft from a position wherein the engaging means are incooperative engagement for achieving an automatic releasing of theengaging means.

11. A structure as defined in claim 10, wherein said member is a splitflanged-collar clampable to the shaft, and said first engaging means isa pair of opposed recesses provided in a face of the flanged collar, andsaid second engaging means is a pivotally mounted latch memberselectively engageable with the recesses.

12. A structure as defined in claim 11, further including a bracketpivotally mounting said latch member and adapted to be mounted on thegear box, and means connected to the bracket and the latch member forbiasing the latch member out of cooperative engagement with therecesses.

1. A shaft lock for an auxiliary sailboat, comprising, in combination:a. a member adapted to be mounted on a propeller shaft of an auxiliarysailboat, and having first means for engaging; b. second means forengaging arrangeable adjacent said member for selectively cooperatingwith the first engaging means and holding the propeller shaft in aposition centering a propeller associated with the shaft behind deadwoodof the sailboat; and c. means for selectively moving the engaging meansinto cooperation with one another, and including means for achieving anautomatic releasing of the engaging means upon a rotation of the shaftwhen the engaging means are in cooperative engagement, said member beinga split flanged-collar clampable to said shaft, and said first engagingmeans being a pair of opposed recesses provided in a face of the flangedcollar, and said second engaging means being a pivotally mounted latchmember selectively engageable with the recesses.
 2. A structure asdefined in claim 1, further including a bracket pivotally mounting saidlatch member and adapted to be mounted on a gear box connected to theshaft, and means connected to the bracket and the latch member forbiasing the latch member out of cooperative engagement with therecesses.
 3. In combination with a sailboat having an auxiliary enginedriving a propeller shaft through a gear box, a shaft lock forpreventing windmilling of a two-blade screw propeller mounted on andturned by said propeller shaft when the sailboat is under said and theauxiliary engine thereof shut down, said shaft lock comprising, incombination: a. a member detachably mounted on the shaft, and havingfirst means for engaging; b. second means for engaging mounted adjacentsaid member for selectively cooperating with the first engaging meansand holding said shaft in one of two opposed positions which center saidpropeller behind deadwood of the sailboat; and c. means for selectivelymoving the engaging means into cooperation with one another, andincluding means for achieving an automatic releasing of the engagingmeans upon a rotation of the shaft when the engaging means are incooperative engagement, said member being a split flanged-collarclampable to said shaft, and said first engaging means being a pair ofopposed recesses provided in a face of the flanged collar, and saidsecond engaging means being a pivotally mounted latch member selectivelyengageable with the recesses.
 4. A structure as defined in claim 3,further including a bracket pivotally mounting said latch member andadapted to be mounted on the gear box, and means connected to thebracket and the latch member for biasing the latch member out ofcooperative engagement with the recesses.
 5. A shaft lock for anauxiliary sailboat, comprising, in combination: a. a member adapted tobe mounted on a propeller shaft of an auxiliary sailboat, and havingfirst means for engaging, said member being a split flanged-collarclampable to the shaft and said first engaging means a pair of opposedrecesses provided in a face of the flanged collAr; b. second means forengaging arrangeable adjacent said member for selectively cooperatingwith the first engaging means and holding the propeller shaft in aposition centering a propeller associated with the shaft behind thedeadwood of the sailboat, said second engaging means being a pivotallymounted latch member selectively engageable with the recesses; c. meansfor selectively moving the second engaging means into cooperation withthe first engaging means, the selectively moving means including a levermember and a rope connected to and extending between said latch memberand said lever member, the selective actuation of the lever memberpivoting said latch member into cooperative engagement with one of saidrecesses, and said lever member being arranged for freely moving upon arotation of the shaft from a position wherein the latch member and arecess are in cooperative engagement for achieving an automaticreleasing of the latch member from the recess; and d. a bracketpivotally mounting said latch member and adapted to be mounted on a gearbox connected to the shaft, and means connected to the bracket and thelatch member for biasing the latch member out of cooperative engagementwith the recesses.
 6. A shaft lock for an auxiliary sailboat,comprising, in combination: a. a member adapted to be mounted on apropeller shaft of an auxiliary sailboat, and having first means forengaging; b. second means for engaging arrangeable adjacent said memberfor selectively cooperating with the first engaging means and holdingthe propeller shaft in a position centering a propeller associated withthe shaft behind deadwood of the sailboat; and c. means for selectivelymoving the second engaging means into cooperation with the firstengaging means, the selectively moving means including a lever memberand a rope connected to and extending between the first and secondengaging means, the selective actuation of the lever member pivotingsaid second engaging means into cooperative engagement with said firstengaging means, and said lever member being arranged for freely movingupon a rotation of the shaft from a position where the engaging meansare in cooperative engagement for achieving an automatic releasing ofthe engaging means.
 7. A structure as defined in claim 6, wherein saidmember is a split flanged-collar clampable to the shaft and said firstengaging means is a pair of opposed recesses provided in a face of saidflanged-collar, and said second engaging means is a pivotally mountedlatch member selectively engageable with the recesses.
 8. A structure asdefined in claim 7, further including a bracket pivotally mounting saidlatch member and adapted to be mounted on a gear box connected to theshaft, and means connected to the bracket and the latch member forbiasing the latch member out of cooperative engagement with therecesses.
 9. In combination with a sailboat having an auxiliary enginedriving a propeller shaft through a gear box, a shaft lock forpreventing windmilling of a two-blade screw propeller mounted on andturned by said propeller shaft when the sailboat is under sail and theauxiliary engine thereof shut down, said shaft lock comprising, incombination: a. a member detachably mounted on the shaft, and havingfirst means for engaging said member being a split flanged-collarclampable to said shaft, and said first engaging means a pair of opposedrecesses provided in a face of the flanged collar; b. second means forengaging mounted adjacent said member for selectively cooperating withthe first engaging means and holding said shaft in one of two opposedpositions which center said propeller behind deadwood of the sailboat,said second engaging means being a pivotally mounted latch memberselectively engageable with the recesses; c. means for selectivelymoving the second engaging means into cooperation with the firstengaging means, the selectively moving means including a lever memberand a rope connected to and Extending between said latch member and saidlever member, the selective actuation of the lever member pivoting saidlatch member into cooperative engagement with one of said recesses, andsaid lever member being arranged for freely moving upon a rotation ofthe shaft from a position wherein the latch member and a recess are incooperative engagement for achieving an automatic releasing of the latchmember from the recess; and d. a bracket pivotally mounting said latchmember and adapted to be mounted on the gear box, and means connected tothe bracket and the latch member for biasing the latch member out ofcooperative engagement with the recesses.
 10. In combination with asailboat having an auxiliary engine driving a propeller shaft through agear box, a shaft lock for preventing windmilling of a two-blade screwpropeller mounted on and turned by said propeller shaft when thesailboat is under sail and the auxiliary engine thereof shut down, saidshaft lock comprising, in combination: a. a member detachably mounted onthe shaft, and having first means for engaging; b. second means forengaging mounted adjacent said member for selectively cooperating withthe first engaging means and holding said shaft in one of two opposedpositions which center said propeller behind deadwood of the sailboat;and c. means for selectively moving the second engaging means intocooperation with the first engaging means, the selectively moving meansincluding a lever member and a rope connected to and extending betweenthe first and second engaging means, the selective actuation of thelever member pivoting said second engaging means into cooperativeengagement with said first engaging means, and said lever member beingarranged for freely moving upon a rotation of the shaft from a positionwherein the engaging means are in cooperative engagement for achievingan automatic releasing of the engaging means.
 11. A structure as definedin claim 10, wherein said member is a split flanged-collar clampable tothe shaft, and said first engaging means is a pair of opposed recessesprovided in a face of the flanged collar, and said second engaging meansis a pivotally mounted latch member selectively engageable with therecesses.
 12. A structure as defined in claim 11, further including abracket pivotally mounting said latch member and adapted to be mountedon the gear box, and means connected to the bracket and the latch memberfor biasing the latch member out of cooperative engagement with therecesses.